1. Field of the Invention
The present invention relates to surface acoustic wave filters, and more particularly to a surface acoustic wave filter that has a structure in which a lower-layer wiring line and an upper-layer wiring line three-dimensionally cross each other.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2004-282707 discloses an example of a surface acoustic wave filter of the related art. Japanese Unexamined Patent Application Publication No. 2004-282707 discloses a configuration in which a lower-layer wiring line and an upper-layer wiring line that have different potentials cross each other without being electrically connected to each other by interposing an interlayer insulating film therebetween.
FIG. 9 and FIG. 17B of Japanese Unexamined Patent Application Publication No. 2004-282707 illustrate a configuration in which the width of an interlayer insulating film is greater than a line width of an upper-layer wiring line. As illustrated in FIG. 10 of the present application, which is FIG. 9 of Japanese Unexamined Patent Application Publication No. 2004-282707, in the case where the area of an interlayer insulating film is increased, a parasitic capacitance that is generated between the lower-layer wiring line and the upper-layer wiring line in an area in which the lower-layer and upper-layer wiring lines three-dimensionally cross each other increases. There has been a problem in that characteristics of a surface acoustic wave filter deteriorate when an undesirable signal leaks out to the lower-layer wiring line from the upper-layer wiring line through the parasitic capacitance.